linux-kernel - Re: [PATCH 1/2 v2] xhci: fix garbage USBSTS being logged in some cases

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Message-ID: <01054a96-22d1-b72e-1166-fcbd5c2f489b@linux.intel.com>
Date:   Mon, 28 Feb 2022 13:34:45 +0200
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Anssi Hannula <anssi.hannula@...wise.fi>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2 v2] xhci: fix garbage USBSTS being logged in some
 cases

On 25.2.2022 12.26, Anssi Hannula wrote:
> xhci_decode_usbsts() is expected to return a zero-terminated string by
> its only caller, xhci_stop_endpoint_command_watchdog(), which directly
> logs the return value:
> 
>   xhci_warn(xhci, "USBSTS:%s\n", xhci_decode_usbsts(str, usbsts));
> 
> However, if no recognized bits are set in usbsts, the function will
> return without having called any sprintf() and therefore return an
> untouched non-zero-terminated caller-provided buffer, causing garbage
> to be output to log.
> 
> Fix that by always including the raw value in the output.
> 
> Note that before 4843b4b5ec64 ("xhci: fix even more unsafe memory usage
> in xhci tracing") the result effect in the failure case was different as
> a static buffer was used here, but the code still worked incorrectly.
> 
> Fixes: 9c1aa36efdae ("xhci: Show host status when watchdog triggers and host is assumed dead.")
> Signed-off-by: Anssi Hannula <anssi.hannula@...wise.fi>
> ---

Thanks. Adding both 1/2 v2 and 2/2

-Mathias